The leaders of multiple political parties are demanding they are also invited to any Brexit debates after reports suggested Theresa May will challenge Jeremy Corbyn to a TV showdown on her deal.
The Labour leader said he would “relish a head-to-head” with the Prime Minister to discuss the Withdrawal Agreement she brought back from Brussels.
Now the SNP, the Lib Dems, the Green Party and Plaid Cymru say they should also be involved.
Scottish First Minister Nicola Sturgeon tweeted: “I can’t speak for Jeremy Corbyn, but I’d be up for a full leaders’ debate on the ‘deal’.
“So, how about it PM @theresa_may?”
The SNP’s defence spokesman Stewart McDonald said his party must be included, claiming a debate between Mrs May and Mr Corbyn “would represent the worst type of Westminster carve-up”.
He tweeted: “Any TV debate that takes place on Brexit must include all parties represented in the UK parliament.”
A spokesman for Downing Street refused to confirm whether Number 10 was considering such a debate.
He told reporters on Monday: “The Prime Minister debates the leaders of the opposition parties regularly on Brexit and will be doing so in effect at 3.30pm today (when she makes her statement to the House of Commons).”
In response, Liberal Democrat leader Sir Vince Cable demanded to be involved because neither the Tories nor Labour had called for a second Brexit referendum.
The Greens have also said they must be be included, saying any debate “must be cross-party, featuring a diverse range of voices representing every nation, as well as every stance on this deal and our relationship with the EU”.
Plaid Cymru leader Adam Price tweeted: “People deserve the opportunity to hear from all the different voices on the biggest decision we will make for generations.
“I’m ready to make sure Wales’s voice is heard in any TV debate.”
The PM was accused of “running scared” last year after refusing to appear at any of the TV debates in the run-up to the snap General Election.
But she is embarking on a PR blitz this week as she tries to convince the public to back her Brexit deal and put pressure on MPs to support it as it goes to a vote in Parliament.
Campaigners seeking a second referendum have written to broadcasters, saying that a head-to-head debate would breach impartiality rules.
The People’s Vote campaign said excluding a candidate who backs a new poll would be in breach of the BBC Charter and Ofcom rules on fairness in political broadcasting.
In a letter sent to BBC director-general Lord Hall, ITN chief executive John Hardie and John Ryley, the head of Sky News, they said: “A format agreed hastily between Downing Street, the office of the leader of the Opposition and broadcasters would damage the reputation of TV debates, as well as perhaps, British broadcasting in general.”
The SNP’s depute leader Keith Brown has also written to Sky News urging it to push for a “representative” debate.
He said: “Sky News are right to look to stage a televised Brexit debate but wrong to want to host a head-to-head debate between May and Corbyn.
“The the idea that this is a binary choice between a Tory hard Brexit or a Labour hard Brexit is grossly misleading.
“Labour and the Tories only reflect the views of a limited share of the British public – and an even smaller share of Scottish public, who voted overwhelmingly against Brexit – so it would be a massive mistake for a live leaders’ debate to go ahead without Nicola Sturgeon.
“As other broadcasters have noted, the First Minister of Scotland needs be involved if this is there is to be a truly representative televised debate.
“It is vital that people are able to see all of the options that are being put forward – including the SNP’s position for the whole UK to maintain membership of the Customs Union and Single Market in order to protect jobs and the economy – so all options are properly discussed and scrutinised.”